The invention discloses a device for controlling a pressure difference between a forming department and a hot-cutting department of a glass substrate. The device comprises the forming department and the hot-cutting department partitioned by a partition plate, wherein a mounting hole is formed in the partition plate; an annealing furnace penetrates through the mounting hole and is spaced from the mounting hole to form an annular gap surrounding the annealing furnace; a pedal is used for partially sealing the annular gap, vent holes located in the left and right sides of the annealing furnace respectively are formed between the pedal and the annealing furnace; the vent holes extend along the length direction of the annealing furnace; a baffle used for adjusting the openness of the vent holes is arranged on the pedal; fixed components are fixed to the front and rear sides of the baffle respectively to clamp or loosen the baffle. The fixed components on the left and right sides of the baffle can be adjusted, the distance between the baffle and the annealing furnace is adjusted, the openness of the vent holes is adjusted, the pressure difference between the forming department and the hot-cutting department is further controlled, and the fixed components are fixed to the pedal, thereby keeping the stable pressure difference between the forming department and the hot-cutting department, and ensuring the stability of quality of a product.